Microelectronic device processing, such as semiconductor fabrication, may utilize various process gases. Gases utilized in microelectronic device processing may not be completely used up during processing and may be left over as waste gas. In order to prevent waste gas from escaping to the environment, scrubbers may be provided to neutralize the waste gas.
FIG. 1 is a schematic block diagram of a conventional exhaust gas system for treating waste gas from microelectronic device processing. A process gas stored in a gas cabinet 10 is fed into a process chamber 20 where microelectronic device fabrication processing is carried out. A vacuum pump 30 pumps process gas remaining in the process chamber 20 into a scrubber 40, via a first suction tube 1, where the process gas is cleaned, neutralized and exhausted using cleaning water. However, when the scrubber 40 is used for a long time, the cleaning water may be discharged from the scrubber together with the processed gas, which may result in operational problems. Therefore, conventional gas exhaust systems may include a residue removing and blocking apparatus 50 connected to the scrubber 40, via a second suction tube 2, in order to prevent cleaning water from being discharged from the scrubber.
Referring to FIG. 2, a schematic perspective view of a conventional residue removing and blocking apparatus for a gas exhaust system is provided. The residue removing and blocking apparatus 50 includes a container 50a that is formed of transparent polyvinyl chloride (PVC), and that contains a plurality of filtering members or absorbers 50b that may also be formed of transparent PVC. The container 50a is connected to a suction pump 60 as illustrated.
Cleaning water that is exhausted with a process gas is pulled via the suction pump 60, into the container 50a of the residue removing and blocking apparatus 50 through the suction tube 2. The cleaning water pulled in with the process gas is absorbed by the filtering absorbers 50b so that the processed waste gas can be exhausted free of cleaning water entrained therein. In effect, the processed waste gas is "dehumidified."
Generally, the residue removing and blocking apparatus 50 is cleaned on a periodic basis, such as every couple of days. Cleaning protects against operational failure of the gas exhaust system due to degradation in the efficiency of the residue removing and blocking apparatus 50. Unfortunately, conventional residue removing and blocking devices may have several disadvantages. Cleaning water may not be completely absorbed by the filtering absorbers and may be exhausted with the processed waste gas which may result in pollution or damage to other parts of the processing equipment. Other process residual material may be pulled into the residue removing and blocking apparatus together with the cleaning water.
The process residual material may be absorbed into the absorbers and changed into a powder form. The residue powder may block off the input line for the cleaning water, which may serve as an obstacle to smooth and efficient performance of a suction pump. Furthermore, the amount of cleaning water may be considerably reduced because of a blocked input line. In addition, the residue powder may be discharged out of the system causing environmental pollution. The residue removing and blocking apparatus may require periodic cleaning, which may reduce operational efficiency of the microelectronic device processing.